Organosilanes and organosiloxanes containing polyfluorinated hydrocarbon radicals bonded to silicon by means of carbon atoms, oxygen atoms, or both are reported in the prior art. Resinous siloxane copolymers containing (C.sub.n F.sub.2n+1 CH.sub.2 CH.sub.2)(CH.sub.3).sub.2 SiO.sub.1/2 units, where the value of n is from 1 to 10, and SiO.sub.4/2 units are disclosed in U.S. Pat. No. 3,328,349 which issued on June 27, 1967 to C. W. Lentz. The patent teaches that the disclosed resins are useful as waterproofing agents and surfactants, for improving the strength of silicone rubber and as defoaming agents.
The products disclosed in the aforementioned Lentz patent are prepared by reacting a silane of the formula C.sub.n F.sub.2n+1 CH.sub.2 CH.sub.2 (CH.sub.3).sub.2 SiCl and/or a disiloxane of the formula [C.sub.n F.sub.2n+1 CH.sub.2 CH.sub.2 (CH.sub.3).sub.2 Si].sub.2 O, where n has a value of from 1 to 10, with sodium silicate which has been at least partially hydrolyzed using a mixture of concentrated aqueous hydrochloric acid and an alcohol such as ethanol or propanol. The cost of synthesizing the fluorine-containing silane and disiloxane reactants taught by Lentz could considerably increase the cost of the final resin.
U.S. Pat. No. 3,038,000 to Schmidt, which issued on June 5, 1962, discloses silanes and siloxanes containing fluorinated groups of the formula XF.sub.2 C(CF.sub.2).sub.m CH.sub.2 OOC(CH.sub.2).sub.n --and optionally, XF.sub.2 C(CF.sub.2).sub.m CH.sub.2 O--bonded to silicon, where m and n are integers with a value of at least 2. These materials are allegedly useful as waterproofing and soilproofing agents for cellulosic materials and as lubricants which can function under high pressure conditions. The disclosed silanes and siloxanes are prepared by reacting a 1,1-dihydroperfluoro alcohol with silanes or siloxanes containing an omega-carboxyalkyl or omega-cyanoalkyl radical and, optionally, one or more chlorine atoms, bonded to silicon. The alcohol reacts with the carboxyl or cyano group in addition to reacting with any halogen atoms present in the organosilicon material. A disadvantage of the method taught by Schmidt is that it employs silanes or siloxanes containing cyanoalkyl or carboxyalkyl radicals bonded to silicon. As in the case of the aforementioned Lentz patent, synthesis of the required intermediates could add considerably to the cost of preparing the final product.
U.S. Pat. No. 3,511,788, which issued to J. Keil on May 12, 1970, discloses that stable foams can be prepared from organic liquids having surface tensions of at least 22.2 dynes per centimeter by including in the foamable composition a siloxane copolymer containing SiO.sub.4/2 units Q(CH.sub.3).sub.2 SiO.sub.1/2 units and (CH.sub.3).sub.3 SiO.sub.1/2 units, where Q represents a "radical containing a solubilizing group." The purpose of the Q group is to make the copolymer compatible with organic liquids and plastisols with which it would otherwise be incompatible. It cannot be deduced from the teaching in the patent what effect the copolymers disclosed by Keil would have on the stability of foams or froths prepared from liquid polydimethylsiloxane compositions, which are outside the scope of the aforementioned Keil patent in that they typically exhibit surface tension values below Keil's lower limit of 22.2 dynes per centimeter.
It is an object of this invention to provide a novel class of fluorine containing polyorganosiloxanes that can be conveniently synthesized from available organosilicon reactants without requiring the preparation of relatively costly organosilicon intermediates.
It is also an object of this invention to provide foamable compositions comprising a liquid polydimethylsiloxane and one of the preferred fluorine-containing polyorganosiloxanes of this invention as a foam stabilizer.